This article summary SHOULD have compared this to a background risk of 3-5% for birth defects in the general population, making these findings less striking-other then the cluster of brain anomalies.
1 in 20 Zika-Affected Pregnancies in U.S. Territories Results in Birth Defects — Physician’s First Watch
1 in 20 Zika-Affected Pregnancies in U.S. Territories Results in Birth Defects
By Kelly Young
An estimated 1 in 20 pregnancies with possible Zika infection in U.S. territories results in birth defects, according to an analysis of hospital records in MMWR. This figure is consistent with data reported from a smaller study of Zika in U.S. states.
From January 2016 through April 2017, over 2500 live births and pregnancy losses in U.S. territories (e.g., Puerto Rico, U.S. Virgin Islands) had lab evidence of possible Zika infection. Of these, 5% had birth defects.
When the analysis was limited to maternal Zika infections that occurred in the first trimester and were confirmed with RNA nucleic acid tests, the rate of birth defects was 8%. When infection occurred in the second and third trimesters, birth defects still occurred in 5% and 4%, respectively, "suggesting a risk for birth defects throughout pregnancy," the authors write.
Brain abnormalities and microcephaly were the most common birth defects (89%).
In a press conference on Thursday, CDC officials said that the number of Zika cases in Puerto Rico has decreased substantially in recent months, but cases are still occurring there.